Purposes are a) to develop an animal model for the study of the control of hyperkinesis by stimulant drugs, especially amphetamine, and b) to develop a model for the study of aggression in social systems. Since excessive aggressiveness is sometines associated with hyperkinesis, the feasibility of combining these two objectives is obvious. The projected model is a Telomian x Beagle F1 hybrid dog. Such animals are generally hyperactive and difficult to train in restraint. Pilot experiments by Corson and Ginsburg independently show favorable responses to d-amphetamine sulphate. By comparisons of reciprocal hybrids with the two pure strains the study will establish the incidence of hyperkinesis under two test conditions, one involving solitary inhibitory training, and the other aggressive competition in an organized social system. Selected animals will be sent to Ginsburg and Corson for blind evaluation in different tests. Results should establish the genetic basis of the trait and the degree of individual variation in crosses with various beagle strains. More generally, the model should demonstrate the feasibility and usefulness of F1 hybrids in biomedical research involving dogs.